Question

5. A sample of an unknown metal has a mass of 120.4 g. As the sample cools from 90.5°C to 25.7°C, it releases 7020. J of energy. What is the specific heat of the sample? Identify the metal among those in the data table below. Finally, is this endothermic or exothermic?

Answer 1

Answer: The specific heat capacity of the sample is
`0.899 J/g^(o)C` and as heat is released in this reaction so it is exothermic in nature.

Step-by-step explanation:

Given: Mass = 120.4 g

Heat energy released = -7020 J

Initial temperature =
`90.5^(o)C`

Final temperature =
`25.7^(o)C`

Formula used is as follows.

`q = m * C * (T_(2) - T_(1))`

where,

q = heat energy

m = mass of substance

C = specific heat capacity

`T_(1)` = initial temperature

`T_(2)` = final temperature

Substitute the values into above formula as follows.

`q = m * C * (T_(2) - T_(1))\\-7020 J = 120.4 g * C * (90.5 - 25.7)^(o)C\\C = (-7020 J)/(120.4 * (-64.8^(o)C))\\= (7020 J)/(7801.92) J/g^(o)C\\= 0.899 J/g^(o)C`

When heat is released in a process or reaction then it means it is exothermic in nature.

Thus, we can conclude that the specific heat capacity of the sample is
`0.899 J/g^(o)C` and as heat is released in this reaction so it is exothermic in nature.